Much valuable intellectual property takes audible, visual, or audio-visual forms, and can be transported electronically as digital files or digital streams. Such highvalue information, representable as a digital file or a digital stream, is referred to herein as content. Such content includes books (transmissible forms for print media), popular songs, both in audible form and in audio-visual (‘rock video’) forms, movies, sports broadcasts, and news in a variety of forms including text, audio, or audio-visual. Such digital content is well structured for presentation to end users, however, it is poorly structured for enforcement of ownership rights.
Digital devices and communication networks are now almost pervasive in industrialized nations. Because these systems are digital, the storage, transfer and reproduction of data can be performed flawlessly; each successive copy of a digital file may be made precisely the same as the original. This ability to copy and transfer digital data with virtually no loss in quality is having a great impact on many digital rights holders, including music, movie and software producers.
Many techniques for protecting the intellectual property rights of these digital content and software producers have been proposed but have had little success.
Currently, the protection of this intellectual property is provided by means which separate the protection from the content. For example, if the content is protected by encryption, it cannot be used without decryption, and the device or program which performs the decryption is separate from the file or stream containing the encrypted content.
This model does have an advantage in that a media player can be distributed once and then can handle various forms of content. However, content files are now becoming sufficiently large that the resource savings from using a single, universal player, is becoming less and less significant. A two-minute movie trailer, for example, may require 4 MB (megabytes, or millions of bytes) of data, while a simple MPEG (motion picture experts group) player may only require 80 KB (kilobytes); 2% of the size of the data file. As well, universal media players have a number of weaknesses as noted below.
First, the media player, since it covers much content, is re-used a great deal. If the protections in the media player are ever compromised, all content played via that media player is exposed. That is, when the media player is separate from the content, it is vulnerable to class cracks: cracking the media player effectively cracks the protection for all content that it can play.
Some audio players, for example, will allow the user to play AVI files (a common format for digital audio files), but because a certain flag has been set in the AVI file, will not allow it to be copied or stored. If the audio player can be modified so that it can no longer detect this flag, then the audio player will allow all AVI files to be copied or stored without restriction.
Also, in practice, the separation of the protection measures from the protected content has meant that the protection is not provided by the content owner. For example, the National Basketball Association (NBA) does not own the media via which NBA games are broadcast or web-cast, and does not provide the hardware or software used to protect this content. Even content owners such as Warner Brothers do not typically own the means whereby the presentation of their content is protected when displayed on a personal computer (PC) or transmitted via a set-top box on a television set. Hence, the separation requires that the content owner trust intermediaries in order to be paid for providing it.
Digital marking may be used to provide legally enforceable copyright protection.
The two most common digital marking techniques are: 1. watermarking; the embedding of a hidden copyright message in a data file; and 2. fingerprinting; the embedding of a hidden identification number such as a serial number in a data file. (see, for example, Protecting Ownership Rights ThroughDigital Watermarking, H. Berghel and L. O'Gorman, 1996, IEEE Computer 29: 7, pp. 101-103, and Protecting Digital Media Content, Nasir Memon and Ping Wah Wong, 1998, Communications of the ACM 41: 7, pp. 34-43). Additional marking techniques are known in the art.
However, the nature of digital media makes it so difficult to provide effective digital marking that some consider it impossible to provide an indelible digital mark (i.e., one which must be preserved if the content is substantially preserved). Memon et al provide commentary on this, as do Fabien A. P. Petitcolas, Ross J. Anderson, and Markus G. Kuhn in Attacks on Copyright Marking Systems” 1998, 2nd Workshop on Information Hiding, LNCS vol. 1525 (isbn 3-540-65386-4), pp. 218-238. In this case, the separation of the protection (legal enforcement) from the would-be protection (the watermark) is not the problem: rather, the easy erasure of the mark is.
Digital marking, were it truly feasible, would provide an alternative protection model, based on legal enforcement (as with the current copyright for printed matter).
However, it is currently trapped between two incompatible needs (see Memon et al, Bender et al, or W. Bender, D. Gruhl, N. Morimoto, and A. Lu. 1996. Techniques for data hiding. IBM Systems Journal 35: 3-4, pp. 313-336, for example). A digital mark is a steganographic embedding of a copyright message or an identification code in a digital information stream (such as a video or audio stream). Its concealment from the attacker is required so that it cannot be removed trivially. Hence, it must affect those aspects of the data stream which are unimportant to the content as perceived by the human viewer or listener. One such technique is to store a digital mark in the least significant bits of data points which are not critical to the user's enjoyment of the data file.
However, an attacker, knowing that the digital mark is embedded in such ‘perceptually irrelevant ’ information, can simply scramble all such perceptually unimportant aspects of the data stream or data file, thereby either erasing the mark or rendering it sufficiently ambiguous that it becomes useless.
That is, the very nature of digital media-the digitization of a perceptually imprecise analog signal=militates against the feasibility of indelible digital marking in such media files or streams. While this problem may well be solved in the long run, in the current state of the art, it remains an unsolved problem (even if it were solved, it would still be safer to deploy it in concert with the instant invention, in order to increase the protection of the digital content).
There is therefore a need for a method and system of handling and distributing digital media in a manner which is secure against attack. This method and system should preferably reduce the content owner's cost of content presentation to consumers, and to change the nature of the protected entity so that effective digital watermarking is feasible.